text: /*
   * AVRn decoder
   * Copyright (c) 2012 Michael Niedermayer
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "avcodec.h"
  #include "internal.h"
  #include "mjpeg.h"
  #include "mjpegdec.h"
  #include "libavutil/imgutils.h"
  
  typedef struct {
      AVCodecContext *mjpeg_avctx;
      int is_mjpeg;
      int interlace;
      int tff;
  } AVRnContext;
  
  static av_cold int init(AVCodecContext *avctx)
  {
      AVRnContext *a = avctx->priv_data;
      int ret;
  
      // Support "Resolution 1:1" for Avid AVI Codec
      a->is_mjpeg = avctx->extradata_size < 31 || memcmp(&avctx->extradata[28], "1:1", 3);
  
      if(!a->is_mjpeg && avctx->lowres) {
          av_log(avctx, AV_LOG_ERROR, "lowres is not possible with rawvideo\n");
          return AVERROR(EINVAL);
      }
  
      if(a->is_mjpeg) {
          AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_MJPEG);
          AVDictionary *thread_opt = NULL;
          if (!codec) {
              av_log(avctx, AV_LOG_ERROR, "MJPEG codec not found\n");
              return AVERROR_DECODER_NOT_FOUND;
          }
  
          a->mjpeg_avctx = avcodec_alloc_context3(codec);
  
          av_dict_set(&thread_opt, "threads", "1", 0); // Is this needed ?
          a->mjpeg_avctx->refcounted_frames = 1;
          a->mjpeg_avctx->flags = avctx->flags;
          a->mjpeg_avctx->idct_algo = avctx->idct_algo;
          a->mjpeg_avctx->lowres = avctx->lowres;
          a->mjpeg_avctx->width = avctx->width;
          a->mjpeg_avctx->height = avctx->height;
  
          if ((ret = ff_codec_open2_recursive(a->mjpeg_avctx, codec, &thread_opt)) < 0) {
              av_log(avctx, AV_LOG_ERROR, "MJPEG codec failed to open\n");
          }
          av_dict_free(&thread_opt);
  
          return ret;
      }
  
      if ((ret = av_image_check_size(avctx->width, avctx->height, 0, avctx)) < 0)
          return ret;
  
      avctx->pix_fmt = AV_PIX_FMT_UYVY422;
  
      if(avctx->extradata_size >= 9 && avctx->extradata[4]+28 < avctx->extradata_size) {
          int ndx = avctx->extradata[4] + 4;
          a->interlace = !memcmp(avctx->extradata + ndx, "1:1(", 4);
          if(a->interlace) {
              a->tff = avctx->extradata[ndx + 24] == 1;
          }
      }
  
      return 0;
  }
  
  static av_cold int end(AVCodecContext *avctx)
  {
      AVRnContext *a = avctx->priv_data;
  
      avcodec_close(a->mjpeg_avctx);
      av_freep(&a->mjpeg_avctx);
  
      return 0;
  }
  
  static int decode_frame(AVCodecContext *avctx, void *data,
                          int *got_frame, AVPacket *avpkt)
  {
      AVRnContext *a = avctx->priv_data;
      AVFrame *p = data;
      const uint8_t *buf = avpkt->data;
      int buf_size       = avpkt->size;
      int y, ret, true_height;
  
      if(a->is_mjpeg) {
          ret = avcodec_decode_video2(a->mjpeg_avctx, data, got_frame, avpkt);
  
          if (ret >= 0 && *got_frame && avctx->width <= p->width && avctx->height <= p->height) {
              int shift = p->height - avctx->height;
              int subsample_h, subsample_v;
  
              av_pix_fmt_get_chroma_sub_sample(p->format, &subsample_h, &subsample_v);
  
              p->data[0] += p->linesize[0] * shift;
              if (p->data[2]) {
                  p->data[1] += p->linesize[1] * (shift>>subsample_v);
                  p->data[2] += p->linesize[2] * (shift>>subsample_v);
              }
  
              p->width  = avctx->width;
              p->height = avctx->height;
          }
          avctx->pix_fmt = a->mjpeg_avctx->pix_fmt;
          return ret;
      }
  
      true_height    = buf_size / (2*avctx->width);
  
      if(buf_size < 2*avctx->width * avctx->height) {
          av_log(avctx, AV_LOG_ERROR, "packet too small\n");
          return AVERROR_INVALIDDATA;
      }
  
      if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
          return ret;
      p->pict_type= AV_PICTURE_TYPE_I;
      p->key_frame= 1;
  
      if(a->interlace) {
          buf += (true_height - avctx->height)*avctx->width;
          for(y = 0; y < avctx->height-1; y+=2) {
              memcpy(p->data[0] + (y+ a->tff)*p->linesize[0], buf                             , 2*avctx->width);
              memcpy(p->data[0] + (y+!a->tff)*p->linesize[0], buf + avctx->width*true_height+4, 2*avctx->width);
              buf += 2*avctx->width;
          }
      } else {
          buf += (true_height - avctx->height)*avctx->width*2;
          for(y = 0; y < avctx->height; y++) {
              memcpy(p->data[0] + y*p->linesize[0], buf, 2*avctx->width);
              buf += 2*avctx->width;
          }
      }
  
      *got_frame      = 1;
      return buf_size;
  }
  
  AVCodec ff_avrn_decoder = {
      .name           = "avrn",
      .long_name      = NULL_IF_CONFIG_SMALL("Avid AVI Codec"),
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_AVRN,
      .priv_data_size = sizeof(AVRnContext),
      .init           = init,
      .close          = end,
      .decode         = decode_frame,
      .capabilities   = AV_CODEC_CAP_DR1,
      .max_lowres     = 3,
  };
  